Apparatus for purifying water containing dissolved organic matters and trace harmful substances

ABSTRACT

Various kinds of wastewater and water such as methane fermentation digestion liquids, domestic wastewater, sewage, service water, culture pond water, wastewater defined by an active sludge law and wastewater from food industries are decomposed, cleaned and treated with a high efficiency with oxygen radicals, hydroxyl radicals and diphenyl para picrihydoral radicals, and injurious materials are decomposed, cleaned and treated by oxidizing and reducing functions. An apparatus for cleaning dissolved organic matters and a trace amount of injurious materials consisting of a anode which is formed or welded by coating clay or glass with a material prepared by mixing 2 to 15% by weight of a transition metal with 1 to 10% of an oxidized transition metal and sintering the glass within a range from 800 to 1500° C. as a glaze or coating a surface of a metal is with a mixture of anatase type titanium oxide, tin oxide, ruthenium oxide and fine particles of platinum as a glaze and sintering the glaze once again at a temperature of 580 to 980° C.

TECHNICAL FIELD

[0001] The present invention relates to a method and an apparatus forcleaning methane fermentation digestion liquids, domestic wastewater,sewage, service water, culture pond water, wastewater produced by anactivated sludge method, wastewater from food industries and the like.

BACKGROUND ART

[0002] Contamination of water environments is being made more and moreserious by developments of industries and economy as well as rising ofliving levels of human lives. Eutrophication of water areas is madeserious by nitrogen, phosphorus and the like which are contained inwastewater produced by agriculture and human lives. Furthermore, healthof mankind is threatened by increase of organic matters, organicchlorine compounds, aromatic compounds, environmental hormones and thelike contained in industrial wastewater. It is deemed difficult tocompletely treat such contaminants by a traditional water treatingmethod such as a biological method. Under the present circumstanceswhere legal regulations on environments are being strengthened, on theother hand, it is desired to construct an efficient wastewater treatingsystem in order to maintain a stable ecosystem for a long time andpreserve water resources having high safeties. It is therefore attemptedto develop a new water treating technique which is to take the place ofthe biological method and an organic wastewater treatment by anelectrochemical technique has been developed in recent years inparticular.

[0003] A characteristic of the electrochemical treating technique liesin integration of technologies in different domains (for example,electronic engineering, catalytic technology, physical chemistry,microbiology and the like) and fusing techniques in different fields,thereby treating organic wastewater containing contaminants which aredeemed hardly decomposable by the biological method.

[0004] The electrochemical treating technique is not only capable ofremoving solid matters and green powder contained in wastewater with ahigh efficiency without using a flocculant agent and suppressing arunning cost at a low level but also produces sludge in an amountsmaller than that of sludge produced by the biological treating methodand allows the sludge to be reutilized as a fertilizer since theelectrochemical technique does not use chemicals.

[0005] The electrochemical treatment has a floating function, anagglomerating precipitating function and an oxidizing function. Thesolid matters and the organic dissolved matters contained in soil waterare removed by these three functions. Out of these functions, theoxidizing function is the most important and can be divided into directoxidation and indirect oxidation. The direct oxidation oxidizes anorganic matter directly on a surface of an oxidized metal by a catalyticfunction of the oxidized metal such as titanium oxide, tin oxide or thelike. The indirect oxidation oxidizes with an ⁻OH radial generated fromwater by anode discharge.

[0006] A reaction formula is:

H ₂ O+M [ ]→M [ ⁻ OH]+H ⁺ +e ⁻  (1)

[0007] A reaction formula of the organic matter by hydroxyl radicals is:

R+[ ⁻ OH]→M [ ]+RO+H ⁺ +e ⁻  (2)

[0008] wherein a reference symbol M [ ] represents an active site on thesurface of the oxidized metal and a reference symbol R designates theorganic matter.

[0009] Ozone sending and irradiation with ultrasonic waves orelectromagnetic ultrasonic waves are available as methods to generateoxygen radicals and hydroxyl radicals. Furthermore, though there hasbeen developed a method which uses an optical catalytic reaction bytitanium oxide, this method generates radicals in an amount small for ahigh input electric power, decomposes injurious materials with a lowefficiency and requires a high cost of an apparatus. Furthermore, ozoneis not effective for fresh water though ozone is deemed effective forsea water containing large amounts of bromine and manganese.

[0010] Furthermore, attention is paid to use of a transition metal suchas cobalt, manganese or the like in combination with hydrogen peroxide.Though it is known the combination of the transient metal and oxygenperoxide generates radicals at an efficiency higher than that of ozone,this method require a delicate technique and final treatment of hydrogenperoxide in an outlet port since hydrogen neroxide has a variability fororganisms high enough to be inhibited from being added to food.

[0011] It is known that the electrochemical treating method allowsoxygen radicals and hydroxyl radicals to be generated with a lifetime of10 μs to 100 ms from existing water molecules when electrons enter poresexisting in a surface of a material which is composed of fine particlesof titanium oxide, tin oxide, ruthenium oxide, platinum or the like (seespecification of Japanese Patent Application No. 11-68862). It is knownthat this radical oxidatively destructs organic substances includingcarbon sources and nitrogen sources as well as hardly decomposablearomatic substances contained in water.

[0012] It is indicated that a specific condition of an electric field tobe applied between electrodes exists and it is necessary to prolong atime of contact between wastewater and a surface of a metal oxide forgeneration of the oxygen radicals and hydroxyl radicals with a highefficiency on the surface of the metal oxide, that it is necessary toclean surfaces of electrodes by transmitting ultrasonic waves when alarge amount of floating suspended matters are contained in wastewater,and that a voltage, a current and an electric field frequency aregoverned by movements of electrons on the surface of the oxidized metalor the surface of the metal.

[0013] Since an invention described in the specification of the abovementioned application poses a problem that generation of superoxideradicals is insufficient in a high frequency region and excessive in alow frequency region, a problem that a current is unstable duringtreatment of wastewater containing a large amount of ions and the like,it is necessary to establish a treating method by combining a lowfrequency low current with a high frequency slight current and contriveto stabilize voltage pulse application when electric resistance of rawwater changes during a treatment.

[0014] In order to solve the problems posed by the invention describedin the specification of the above mentioned application, the applicantapplied “Method and Apparatus for Cleaning Dissolved Organic Matters andTrace Amount of Injurious Materials” (Application 2000-29570 hereinafterreferred to as “specification of preceding application”) on February 2,Heisei 12.

[0015] An invention described in the specification of the precedingapplication disclosed a water purifying method characterized by coatinga surface of a ceramic having a main body of feldspar or silicon withfine particles of titanium oxide, cobalt oxide, tin oxide, rutheniumoxide, iridium oxide, nickel oxide, iron oxide and vanadium oxide, finemetal particles of titanium, cobalt, nickel, silver and gold or a liquidconsisting of a mixture these metals and a solution of the same kinds ofmetal salts, using as an electrode having a positive polarity the abovedescribed metal oxides or metals or the mixture thereof sintered in atemperature region of 800° C. to 1500° C. after a drying treatment anddisposing an electrode which has a cathode made of platinum or titaniumor stainless steel so as to be opposed to an anode for use of theseelectrode as a radical generating zone, continuously flowing wastewaterbetween both the electrodes of these electrodes opposed to each other,causing pulse discharge between the electrodes under conditions of avoltage of 0.2 kV/cm to 20 kV/cm, an average current of 1 μA/cm² to 10mA/cm² and a frequency of 5 Hz to 50 MHz, thereby generating radicals bypartial decomposition of water and oxidatively-reductively decomposingorganic matters and intermediate products thereof dissolved in water.

[0016] Furthermore, the invention described in the specification of thepreceding application disclosed a water cleaning apparatus for carryingout the above described water purifying method.

[0017]FIG. 9 shows an electrode section in which a anode and a cathodeare disposed in opposition to each other. A reference numeral 51 in FIG.9 represents a anode which has a groove extending in a direction ofrunning water denoted by a reference numeral 52. The anode portion 51 isformed by coating a surface of a ceramic (non-metallic inorganicmaterial including glass) having a main body of feldspar or silicon or ametal such as titanium with fine particles of titanium oxide, cobaltoxide, tin oxide, iridium oxide, nickel oxide, iron oxide and vanadiumoxide, metal fine particles of titanium, cobalt, nickel, silver, goldand platinum or a liquid consisting of a mixture of the metals and asolution of the same kinds of metal salts, and sintering or welding themetals in a temperature region of 500° C. to 1500° C. A cathode 53 ismade of platinum or titanium or stainless steel.

[0018] The anode 51 and a cathode 53 are disposed in opposition to eachother and have a configuration in which the electrodes are enclosed byan outside cell 54. For a water treatment, water to be treated is sentfrom a lower portion (indicated by an arrow) to an upper portion of theoutside cell 54 which is made of a high polymer resin such as acrylicresin, polyethylene resin or the like, and an angle θ between bottomsurfaces of both the electrodes opposed to each other and a foot of thecell is set at 30° to 90°, thereby bringing most portion of contaminantsin the water to be treated is brought into secure contact with theanode. The contaminants in the water to be treated are decomposed with ahigh efficiency by radicals which are generated from the anode 51.

[0019]FIG. 10 shown sectional configurations of water treatingapparatuses: (a) showing a cylindrical circular truncated cone electrodetype and (b) showing a truncated pyramid electrode type.

[0020] In FIGS. 10(a) and 10(b) showing the cylindrical circulartruncated cone electrode type and the truncated pyramidal water treatingapparatuses, a reference numeral 73 represents a raw water inlet port, areference numeral 74 designates an anode electrode, a reference numeral75 denotes a cathode electrode, a reference numeral 76 represents anovercoat (serving also as a cathode), a reference numeral 77 designatesa treated water outlet port, a reference numeral 78 denotes a generatedgas discharge port, a reference numeral 79 represents an electricinsulating material and a reference numeral 79 a designates a throughhole formed in the insulating material 79 for passing raw water.

[0021] The truncated pyramid electrode type water treating apparatusshown in FIG. 10(b) uses electrodes which are formed by inserting theanode 74 made of metals and metal oxides into the overcoat 76 of themetallic cathode 75, placing a titanium plate, a platinum plate and aplatinum bar at a center portion, and connecting these plates and bar tothe overcoat portion.

[0022] The cylindrical circular truncated cone electrode type watertreating apparatus shown in FIG. 10(a) has a configuration in which thewater treating apparatus has a cylindrical or circular truncated conicalstructure having an angle θ set at 30° to 90° between bottom surfaces oftwo anodes opposed to each other and a foot of a cell, an inside surfaceand an outside surface of this cylinder are composed of metal surfaceswhich are coated with powders of the above described oxidized metals,powders of the same metals or a mixture liquid consisting of a mixturethereof and salts of the same metals and sintered, a cathode having aform of a round bar or a square bar made of platinum, titanium orstainless steel is disposed at a center location of the cylindricaltruncated cone, an outside of the cylindrical truncated cone is sealedwith an overcoat container consisting of a metal container made oftitanium, stainless steel or the like, a cathode is composed bydisposing the above described overcoat container in a wastewater inletport, a wastewater outlet port and a generated gas outlet port, and aninside surface and an outside surface of the cylindrical truncated coneare used as a radical generating zone so that organic wastewater is sentfrom a portion of having a large diameter inside the cylindricaltruncated cone, comes out to a portion having a small diameter, flowsagain outside the cylindrical truncated cone in a direction reverse tothat inside, and is oxidatively and reductively treated by generatedradicals.

[0023] The truncated pyramidal electrode type water treating apparatusshown in FIG. 10(b) has a configuration in which a anode is configuredas a flat plate having an angle θ set at 30° to 90° between both bottomsurfaces and roots of both electrodes opposed to each other, two flatplates positioned perpendicular to a thickness direction of the flatplate are composed of metal surfaces which are coated with the powdersof the above described oxidized metals, the powders of the metals or themixture liquid consisting of the mixture thereof and salts of the samemetals and sintered, the two flat plates are disposed so as to besymmetrical with regard to a plane, further two side surfaces of the twoflat plates which are not the oxidized metal surfaces are joined using aflat plate having a surface of titanium, stainless steel or the samemetal on one side and composed as a truncated pyramid so as touniformalize an anode voltage, an overcoat container is composed at alocation symmetrical with a metal surface at a center of the truncatedpyramid with regard to a plane by scaling outsides of a cathodeelectrode composed of a titanium plate, a stainless steel plate, aplatinum net or platinum round bar and the truncated pyramid with atitanium or stainless steel container and a cathode is composed bydisposing the above described overcoat container in a wastewater inletport, a wastewater outlet port and a generated gas outlet port so thatinside surfaces and outside surfaces of the two flat plates coated withthe metal oxides serve as a radical generating zone, organic wastewateris sent from a portion having a large diameter or length inside thetruncated pyramid, and organic matters and injurious materials containedin the wastewater coming out to a portion having a small diameter orlength are oxidatively and reductively decomposed and treated bygenerated radicals while the wastewater flows again outside thetruncated pyramid in a direction reverse to that inside.

[0024] Though the water treating apparatus and method described in thespecification of the preceding application are epoch making watertreatment apparatus and method, it has been found that these apparatusand method hardly allow a continuous operation since the continuousoperation results in events such as accumulation of bubbles in a topsection of the apparatus.

[0025] The present invention has an object to provide a water treatingapparatus which is capable of operation continuously.

DISCLOSURE OF INVENTION

[0026] The present invention provides an apparatus for cleaningdissolved organic matters and a trace amount of injurious materialsconsisting of a anode which is formed by mixing clay and/or glass with 2to 15% by weight of transition metals and 1 to 10% of oxidizedtransition metals, sintering the mixture within a range from 800 to1500° C. or coating a surface of a metal such as titanium with a mixtureof fine particles of anatase type titanium oxide, tin oxide, rutheniumoxide and platinum as a glaze and sintering the mixture once again at atemperature from 580 to 980° C.

[0027] Furthermore, the apparatus according to the present invention ischaracterized in that the above described anode is configured in acylindrical form and an electrically conductive metal is fitted in anend of the anode.

[0028] Furthermore, the apparatus according to the present invention ischaracterized in that at least an electrically conductive metal isinserted in parallel with an axis of the above described cylindricalanode.

[0029] Furthermore, the apparatus according to the present invention ischaracterized in that a pulse voltage and a current are applied to theabove described electrically conductive metal.

[0030] Furthermore, the apparatus according to the present invention ischaracterized in that a cathode is disposed at a center of the abovedescribed cylindrical anode. Furthermore, the apparatus according to thepresent invention is characterized in that the above described anode andthe above described cathode are set in a condition where the anode andcathode are submerged in water and connected to an oscillator whichoscillates an average current density of 0.1 μA/cm² to 10 mA/cm² at afrequency of 5 Hz to 50 MHz and a voltage of 0.2 kV/cm to 20 kV.

[0031] Furthermore, the apparatus according to the present invention ischaracterized in that raw water is flowed downward from an upper portionto a lower portion of the side wall of the above described anode andoxidized and cleaned by various kinds of active species (radials)generated between the above described cathode and anode.

[0032] Furthermore, the apparatus according to the present invention ischaracterized by being composed of a anode configured in a form whichhas a rectangular or truncated pyramidal concave portion.

[0033] Furthermore, the apparatus according to the present invention ischaracterized in that a transition oxidized metals is sintered at 580°C. to 980° C. in the concave portion of the above described anode andelectrically conductive metal plates are formed on both sides of theelectrode as a cathode by way of an insulating material.

[0034] Furthermore, the apparatus according to the present invention ischaracterized in that the above described anode measures 5 to 10 mmthick by 5 to 100 cm wide by 10 to 70 cm high.

BRIEF DESCRIPTION OF THE DRAWINGS

[0035]FIG. 1 is a flow chart showing an overall configuration of thewater treating apparatus according to the present invention and atreatment flow.

[0036]FIG. 2 is a perspective view showing an electrode configurationaccording to the present invention.

[0037]FIG. 3 is a diagram showing a third embodiment of the presentinvention: (a) being a perspective view of a hollow truncated circularcone and (b) being a sectional view showing a case where anodes arepiled in multiple stages.

[0038]FIG. 4 is a partially transmitted perspective view showing afourth embodiment of the electrode configuration according to thepresent invention.

[0039]FIG. 5 is a sectional view showing a fifth embodiment of theelectrode configuration according to the present invention.

[0040]FIG. 6 is a sectional view showing a sixth embodiment of theelectrode configuration according to the present invention.

[0041]FIG. 7 is a sectional view showing a seventh embodiment of theelectrode configuration according to the present invention.

[0042]FIG. 8 is a perspective view showing the seventh embodiment of theelectrode configuration according to the present invention.

[0043]FIG. 9 is a sectional view showing an anode and a cathode whichare disposed in opposition to each other in a conventional watertreatment apparatus.

[0044]FIG. 10 is a sectional view showing configurations of an electrodehaving a form of a truncated circular cone and an electrode having aform of a truncated pyramid.

BEST MODE FOR CARRYING OUT THE INVENTION

[0045] Embodiments of the present invention will be described in detailwith reference to the accompanying drawings. FIG. 1 is a flow chartshowing an overall configuration of a water treating apparatus and atreating flow, in FIG. 1, a reference numeral 101 represents an inflowadjusting tank, a reference numeral 102 designates a dust removingscreen, a reference numeral 103 denotes a header tank, a referencenumeral 104 represents a sludge thickening tank, a reference numeral 105designates a sludge thickening tank, a reference numeral 106 denotes afirst electrode tank, a reference numeral 107 represents a first settingtank, a reference numeral 108 designates a second electrode tank, areference numeral 109 denotes a second setting tank, a reference numeral110 represents a temporal reservoir, a reference symbol P1 designates aliquid feeding pump and a reference symbol P2 denotes a flushinghigh-pressure pump.

[0046] Domestic wastewater to be treated (hereinafter referred to as“raw water to be treated”) is flowed into the inflow adjusting tank 101,sent to the screen 102 by the liquid feeding pump P1 and flowed into theheader tank 103 after suspended matters have been removed from thewastewater. The header tank 103 which is disposed for stable watersupply to a next step also has a function to accelerate precipitation.Supernatant in the header tank 103 flows into the first electrode tank106 (oxidizing tank). Since oxygen radical (⁻0) are mainly generated inthe first electrode tank 106 to which a low voltage is applied, organicsubstances contained in the raw water to be treated are oxidized andsolid matters are agglomerated and precipitated.

[0047] A voltage which is applied to the first electrode tank 106(oxidizing tank) is 240 to 500 V and a current density is 40 to 50mA/cm².

[0048] Supernatant water of wastewater which is oxidatively treated bythe first electrode tank 106 flows into the first setting tank 107 for aprecipitating treatment for a definite time and supernatant flows fromthe first setting tank into the second electrode tank 108 (reducingtank). Since hydroxyl radicals (⁻OH) are mainly generated in the secondelectrode tank 108 to which high-voltage pulses are applied, hardlydecomposable substances such as nitrogen in a condition of ammoniacontained in supernatant in the oxidizing tank 106 are decomposed andsolid matters are agglomerated and precipitated.

[0049] A voltage applied to the second electrode tank 108 (reducingtank) is 2000 to 5000 V and a current density is 50 to 70 μA/cm².

[0050] Supernatant water of wastewater treated in the second electrodetank 108 flows into the second setting tank 109 and, after aprecipitating treatment is performed for a definite time, supernatantwater in the second setting tank 109 flows into the temporal reservoir110 and then is discharged.

[0051] Since solid matters and the like are precipitated in each of theelectrode tanks 106 and 108, precipitate is discharged and flowed intothe sludge thickening tank 105 by spraying discharged water at a highpressure into each of the tanks 106 and 108 with a flushinghigh-pressure pump P2 in a condition where the treatment is interceptedas occasion demands. Furthermore, precipitate in each of the settingtanks 107 and 109 is also discharged appropriately into the sludgethickening tank 105.

[0052] Supernatant water in the sludge thickening tank 105 flows intothe sludge thickening tank 104, then is returned into the inflowadjustment tank 101 and treated once again. Solid matters and the likeprecipitated in the sludge thickening tank 105 is discharged and thentreated as solid matters.

[0053]FIG. 2 is a perspective view showing the electrode configurationaccording to the present invention: (a) showing a first embodiment ofthe electrode configuration in which a cathode 2 composed of a single ora plurality of hollow cylindrical, bar-shaped or linear electricallyconductive metals is disposed in parallel with an axis of a hollowcylindrical anode 1.

[0054] The anode 1 is configured in a form of a hollow cylinder, andformed by mixing clay or glass or a mixture thereof with 2 to 15% byweight of a transition metal and 1 to 10% of an oxidized transitionmetal, sintering the mixture in a range from 800 to 1500° C., thencoating the mixture with anatase type titanium oxide, thin oxide,ruthenium oxide and fine particles of platinum as a glaze, and sinteringthe mixture again at a temperature from 580 to 980° C.

[0055]FIG. 2(b) shows a second embodiment of the electrode configurationin which a anode section is composed by covering a anode 2 with a cap 3made of an electrically conductive metal.

[0056] (c) schematically shows a circuit in an electrode tank in which apulse current is applied between two electrodes. A current I₀ to whichis output from an oscillator 4 in shapes of pulses is supplied in adirection indicated by an arrow and discharged between the anode 1 andthe cathode 2. Reference symbols R₀ and R₁ represent resistors.

[0057] The anode 1 and the cathode 2 are kept in a condition submergedin water and connected to the oscillator 4 which oscillates a currenthaving a frequency of 10 to 100 kHz and a current density of 0.1 μA/cm²to 10 mA/cm².

[0058]FIG. 3(a) shows a third embodiment of the electrode configurationin which a anode 1 has a form of a hollow truncated pyramid and a rootangle of 30° to 90°.

[0059]FIG. 3(b) shows an embodiment in which the anode 1 according tothe first embodiment is piled at multiple stages and an outercircumference of each anode 1 is sheathed with an electricallyconductive water scaling material.

[0060] A multi stage assembling mode is adopted for the electrode tankin view of easy manufacturing of the overcoat. A fixed portion at alower part of the electrode section of the electrode tank is fixed witha bolt or the like and composed of an insulating water sealing materialas a whole.

[0061] Formed at a connected part of each anode 1 is a connecting part 6made of the insulating water sealing material and formed in theconnecting part 6 is a path 6 a for the raw water. It is possible toselect for the raw water either of a case where the raw water is flowedfrom an upper section to a lower section of the apparatus and a casewhere the raw water is flowed from the lower section to the uppersection of the apparatus, and raw water is flowed from a lower sectionto an upper section of an apparatus in a conventional example shown inFIGS. 9 and 10.

[0062] A fourth embodiment of the electrode configuration is shown inFIG. 4, in which a reference numeral 21 represents an anode, a referencenumeral 22 designates a cathode, a reference numeral 23 denotes acleaning water spraying port for cleaning an interior of the electrodetank with cleaning water from a cleaning pipe connected to a highpressure pump, a reference numeral 25 represents an overcoat having anouter circumference treated with a water sealing material, a referencenumeral 27 designates a flange, a reference numeral 28 denotes a cap, areference numeral 29 a represents a raw water inlet port, a referencenumeral 29 b designates a treated water outlet port, a reference numeral29 c denotes a liquid bubble discharge port, a reference numeral 6represents a connecting part made of the water sealing material and areference numeral 6 b designates an insulating-supporting part forconnecting a lower portion of an electrode 1 to the connecting part. Apath 6 a for precipitate is formed in the connecting part 6 though notshown.

[0063] The electrode 1 is inserted into the overcoat 25 in anappropriate number, lower portions of the electrodes 1 are fixed to theconnecting part 6 with the insulating-supporting parts 6 b and upperportions of the electrodes 1 are fixed to a water sealing plate (notshown) made of the water sealing material which is disposed on theflange. The anodes 1 and a cathode 2 are connected to a power source byway of electrode supporting metal fittings 1 a, 2 a and an insulatedconductor.

[0064] The liquid bubble discharge port 29 c serves for dischargingbubbles to be produced in a water surface H located above the raw waterinlet port 29 a.

[0065] A fifth embodiment of the electrode configuration is shown inFIG. 5, in which a reference numeral 21 represents a cylindrical anode,a reference numeral 22 designates a cylindrical cathode, a referencenumeral 23 denotes a nozzle (cleaning water spraying port), a referencenumeral 24 denotes a nozzle (cleaning water spraying port) disposed at acenter portion, a reference numeral 25 represents an outside pipe(overcoat), a reference numeral 26 designates a non-metallic net likeshield which is formed so as to cover an outer circumference of theovercoat.

[0066] The cylindrical cathode 22 is configured to have a form of ahollow cylinder, a through hole formed in an outer circumference thereofand a top portion connected to a cleaning pipe so that cleaning watershoots out of the cathode.

[0067] A sixth embodiment of the electrode configuration which is acylindrical, electrode configuration is shown in FIG. 6, in which areference numeral 31 represents a cathode, a reference numeral 32designate anodes, a reference numeral 34 denotes an outsidepipe(overcoat) and a reference numeral 35 represents a shield. In thisembodiment, the cathode is configured to have a form of a hollowcylinder, and the anodes 32 are disposed as arch-like electrodes on acircumference around the cathode 31 which has radii of R1 and R2(R2=R1/2), whereby an entire surface of the outside pipe 35 is coveredwith the anodes 32 and 33 as seen from the cathode 31.

[0068]FIG. 7 shows a seventh embodiment of the electrode configurationin which the electrode configuration has a rectangular shape: (a) beinga sectional view and (b) being a perspective view. In FIG. 7, areference numeral 41 represents a cathode, a reference numeral 42designates an anode which supports an electrically conductive body madeof a metal oxide, a reference numeral 43 denotes a welded layer (anode)or sintered layer composed of a metal oxide, a reference numeral 44represents an insulator, a reference numeral 45 designates a raw waterpassing hole and a reference numeral 46 denotes an insulator forinsulating rectangular electrodes to be laminated in a plurality oflayers from one another. The insulators 44 and 46 are made of a ceramic.

[0069] The anode 42 having a trapezoidal section is disposed so that anangle θ formed between a surface of the cathode 41 and an oblique lineof the anode is set at 30° to 90°. The trapezoidal anode 42 is disposedbetween the cathodes 41 which are arranged in parallel. Formed inconcave portions of the anodes 42 are metal oxide layers 43 by welding atransition oxidized metal or sintering the transition oxidized metal at580 to 980° C. and disposed on both side of a convex portion of theanode 42 are the insulators 44. The anode 42 is configured to be incontact with an electrically conductive metal plate which is the cathode41.

[0070] The anode 42 is configured as a segment which has dimensions of 5to 10 mm high by 50 to 100 cm wide by 10 to 70 cm high.

[0071] As apparent from FIG. 8, raw water rises in a direction indicatedby an arrow A, passes through a passing hole 45 and flows in a directionindicated by an arrow B in a seventh embodiment.

INDUSTRIAL APPLICABILITY

[0072] The apparatus according to the present invention is capable ofperforming a stable treatment even by combining a low frequency-lowcurrent with a high frequency-slight current since hydroxyl radicals andoxygen radicals are generated stably in a high frequency region and alow frequency region, and a current is supplied stably and consumedpower is reduced even in a treatment of wastewater containing a largemount of ions.

[0073] Furthermore, the apparatus is applicable to a water treatmentfacility on a large scale since the apparatus is capable of operatingcontinuously. Furthermore, even when electric resistance of raw waterchanges during a treatment, the apparatus is capable of performing astable treatment with an adjustment of a pulse voltage to be applied.

[0074] The apparatus exhibits a remarkable effect for cleaning domesticwastewater and removal of blue powder in particular in addition toeffects to use no chemical, require a small area for a facility andfacilitate operations.

1. An apparatus for cleaning dissolved organic matters and a trace amount of injurious materials consisting of a anode formed or welded by mixing clay and/or glass with a material which is prepared by mixing 2 to 15% by weight of a transition metal and 1 to 10% of an oxidized transition metal and sintered within a range from 800 to 1500° C. or coating a surface of a metal with a material prepared by mixture of anatase type titanium oxide, tin oxide, ruthenium oxide and fine particles of platinum as a glaze, and sintering the mixture once again at a temperature of 580 to 980° C.
 2. The apparatus for cleaning dissolved organic substances and a trace amount of injurious materials according to claim 1, characterized in that said anode is configured in a cylindrical form and an electrically conductive metal is fitted in an end of the anode.
 3. The apparatus for cleaning dissolved organic substance and a trace amount of injurious materials according to claim 1, characterized in that at least an electrically conductive metal is inserted in parallel with an axis of said cylindrical anode.
 4. The apparatus for cleaning dissolved organic substances and a trace amount of injurious materials according to claim 2 or 3, characterized in that a pulse voltage and a current are applied to said electrically conductive metal.
 5. The apparatus for cleaning dissolved organic substance and a trace amount of injurious materials according to any one of claims 1 to 3, characterized in that a cathode is disposed at a center of said cylindrical anode.
 6. The apparatus for cleaning dissolved organic substance and a trace amount of injurious materials according to claim 2 or 3, characterized in that said anode and said cathode are kept in a condition submerged in water and connected to an oscillator which oscillates an average current density of 0.1 μA/cm² to 10 mA/cm² at a frequency of 5 Hz to 50 MHz and a voltage of 0.2 kV/cm to 20 kV.
 7. The apparatus for cleaning dissolved organic substances and a trace amount of injurious materials according to claim 2 or 3, characterized in that raw water is flowed downward from an upper portion of a side wall of said anode and is oxidized and cleaned by various kinds of active species (radicals) generated between said cathode and an anode.
 8. The apparatus for cleaning dissolved organic substances and a trace amount of injurious materials according to claim 2 or 3, characterized by being composed of a anode configured in a form which has a rectangular or truncated pyramidal concave portion.
 9. The apparatus for cleaning dissolved organic substance and a trace amount of injurious materials according to any one of claims 1 to 3, characterized in that a transition metal oxide is sintered in the concave portion of said anode at 580 to 980° C. and electrically conductive metal plates are formed on both side of the electrode as a cathode by way of an insulator.
 10. The apparatus for cleaning dissolved organic matters and a trace amount of injurious materials according to any one of claims 1 to 3, characterized in that said anode measures 5 to 10 mm thick by 5 to 100 cm wide by 10 to 70 cm high. 